Codechange: Use FindVehiclesWithOrder when removing a road stop.

[PeterN]

Motivation / Problem

When removing a road stop tile, the road vehicle pool is iterated to find any road vehicles that are currently heading to the tile, so they can be rerouted. This can take time if there are a lot of vehicles.

Description

Road vehicles can only have the road stop tile as their destination if it is in their order lists, and searching shared order lists can be faster than searching the vehicle pool.

Search for vehicles with the road stop in their orders, and then reroute if their destination is the removed tile.

The change is inconsequential with most saves, however when road stops are removed in bulk (company bankrupt/reset) it can add up.

Save	Master	This PR
Wentbourne remove 1 road stop	28µs	6µs
Wentbourne reset_company 1	39,422µs	7,981µs
Xarick's 4kx4k remove 1 road stop	5,380µs	299µs
Xarick's 4kx4k stop_ai 2	7,531,394µs	418,717µs

Limitations

Checklist for review

Some things are not automated, and forgotten often. This list is a reminder for the reviewers.

• The bug fix is important enough to be backported? (label: 'backport requested')
• This PR touches english.txt or translations? Check the guidelines
• This PR affects the save game format? (label 'savegame upgrade')
• This PR affects the GS/AI API? (label 'needs review: Script API')
  • ai_changelog.hpp, game_changelog.hpp need updating.
  • The compatibility wrappers (compat_*.nut) need updating.
• This PR affects the NewGRF API? (label 'needs review: NewGRF')
  • newgrf_debug_data.h may need updating.
  • PR must be added to API tracker

[LordAro]

What happens when the number of orders is significantly larger than the list of vehicles? :)

[PeterN]

What happens when the number of orders is significantly larger than the list of vehicles? :)

Would a savegame with non-shared orders suffice? Or shall I fabric a savegame with 255 non-shared orders for every vehicle...

[PeterN]

Yup, 5000 road vehicles with 255 unshared orders each, is considerably slower this way.

Master: 80µs
This PR: 3,675µs

[TrueBrain]

@LordAro let's not backport these kind of changes moments before release. Feels like asking for trouble, don't you agree? :)